A compact lightweight planar antenna using waveguide has been described for use in space limited applications such as aircraft and satellite communications. Such a planar antenna may be configured to operate with two different polarization states to provide polarization diversity to preclude the need for two physically separate antennas. U.S. Pat. No. 6,127,985 ('985 patent) describes such an antenna; the '985 patent is hereby incorporated by reference in its entirety.
However, the planar antenna disclosed in the '985 patent has limited bandwidth, is of rectangular shape, and has equal antenna element power levels (uniform amplitude distribution). It is well-known that the uniform amplitude distribution over the planar aperture leads to predictable but sometimes higher-than-desired antenna pattern sidelobe levels depending upon the intended application. There is a need for such a compact planar antenna with dual polarization states that has increased bandwidth, is not constrained to a rectangular boundary, and can have a tapered amplitude distribution which leads to reduced antenna pattern sidelobe levels.